* device/lib/pic16/libc/stdio/sprintf.c: return the number of

* device/lib/pic16/libc/stdio/sprintf.c: return the number of
  characters printed (not including the trailing '\0' used to end
  output to strings). Problem detected in regression test bug-927659.c.
  NOTE: printf() family functions should return int instead
  unsigned int!
* device/lib/pic16/libc/stdio/vfprintf.c: "%%" prints "%", unknown
  specifier are printed as themselves
* sdcc/support/regression/tests/bug1057979.c: pic16 printf doesn't
  support flags, width and precision specifiers

git-svn-id: https://sdcc.svn.sourceforge.net/svnroot/sdcc/trunk/sdcc@4249 4a8a32a2-be11-0410-ad9d-d568d2c75423